The invention relates to a device for measuring the fuel consumption of a vehicle, with means for measuring the fuel forward flow in a forward flow line, and the fuel return flow in a return flow line, having means for detecting the difference between these flows and for the calculation of the fuel consumption based thereon.
Such devices are needed in order to measure the fuel consumption in modern motor vehicles, wherein a fuel forward flow to the carburetor or to an injector, and a fuel return flow of the fuel return flow are to prevent the fuel, even at extreme environmental conditions, from heating up too much, which may cause disturbances in the operation of the motor vehicle. Usually, the fuel forward flow is set to a constant flow, e.g., 120 liters per hour, with an electrically driven fuel pump, and at lower fuel consumption the return flow is approximately just as large.
In the measurement of the fuel consumption by measuring the flows of the fuel forward flow and the fuel return flow by means of the difference therebetween, the problem arises that the differences between great numerical values must be formed, in which computation the errors of measurement in the determination of one of the values corresponding to the forward flow and the return flow may be greater than the difference of these numerical values.